STP may refer to any of the following:
1. Short for Spanning Tree Protocol, STP is a networking protocol first designed by Radia Perlman. It creates a single path over a network, preventing any loops from occurring, even if there are multiple paths to the same destination.
2. Short for Shielded Twisted Pair, see the STP cable definition for further information.
3. Short for Software Test Plan, STP is a plan developed as a guideline to test computer software.
4. STP is a file extension for 3-D assembly files, used to transfer 3-D graphics between CAD programs.